In speaker or voice recognition, goats can refer to authorized end-users that are prevented from accessing a system because their biometric data pattern (e.g., speech pattern) is not within a range that is recognized by the system. For example, goats can be speakers with poor quality biometric models that result in a lack of success at being accepted into a system. Wolves can refer to unauthorized end-users that compare well with target biometric models, and are granted access to a system. In other words, wolves can refer to speakers that are successful at impersonating the biometric characteristics required for access to a system. See, e.g., G. Doddington et al., “SHEEP, GOATS, LAMBS and WOLVES: A Statistical Analysis of Speaker Performance in the NIST 1998 Speaker Recognition Evaluation”, in Proc. ICSLP, 1998.
In order to ensure adequate performance of a speaker recognition system, goats and wolves should be properly identified.